JP4661908B2 - Heat pump unit and heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump unit, and more particularly, to a heat pump unit and a heat pump hot water supply device used in a hot water circulation heating system that performs heating by circulating hot water in a building.

  2. Description of the Related Art Conventionally, there are heat pumps, hot water storage tanks that store hot water heated by the heat pumps, and hot water circulation heating systems that heat the buildings by circulating the hot water to radiators provided in each room in the building. The heat pump is installed outdoors, and includes a compressor, a radiator, an expansion valve, and an evaporator that are connected by refrigerant piping and constitute a refrigeration cycle, and a fan that applies outside air to the evaporator. Here, the heat pump takes heat from the outside air by the evaporator and heats the hot water flowing from the hot water storage tank by the heat released from the radiator.

  However, since the heat pump takes heat from the outside air by the evaporator, the water vapor in the air condenses and the condensed water adheres to the evaporator that collects heat from the outside air. In a situation where the outside air temperature is relatively high, this condensed water is discharged out of the apparatus through a drain outlet provided in the drain pan of the evaporator. However, in cold districts such as Europe, the temperature of the outside air often drops to below freezing in winter when heating operation is performed, so the drain outlet may freeze and drainage failure may occur.

  If condensed water that is not discharged to the outside due to poor drainage is frosted or frozen by the evaporator, the evaporation capacity of the evaporator decreases, the heating capacity decreases, and the refrigerant pipes and sheet metal may be damaged.

Therefore, in the heat pump disclosed in Patent Document 1, the defrosting operation of the evaporator is performed using the heat of a part of the refrigerant discharged from the compressor and before entering the radiator.
JP 2007-155296 A

  However, when the defrosting operation of the evaporator is performed by the heat of the refrigerant discharged from the compressor and before entering the radiator, the temperature of the refrigerant entering the radiator may be lowered, and the heat efficiency of the heat pump unit may be lowered.

  The subject of this invention is providing the heat pump unit which can prevent the freezing of the drain outlet of the drain pan provided in the evaporator.

The heat pump unit according to the first invention includes an evaporator, a compressor, a radiator, a decompression mechanism, a drain pan, a drain pan heating means, and a heat exchanger. The evaporator absorbs heat in the air and evaporates the refrigerant. The compressor compresses the gas-phase refrigerant from the evaporator and discharges it as a high-pressure refrigerant. The radiator releases the heat of the high-temperature refrigerant supplied from the compressor. The decompression mechanism expands the refrigerant from the radiator. The drain pan is a tray that is provided in the lower part of the evaporator to discharge condensed water. The drain pan heating means heats the drain pan using the heat of at least a part of the refrigerant flowing between the radiator and the decompression mechanism. The heat exchanger performs heat exchange between the refrigerant from the evaporator toward the compressor and the refrigerant from the radiator toward the decompression mechanism, and provides supercooling to the refrigerant that has flowed out of the radiator . In the heat exchanger, the refrigerant discharged from the radiator and flowing in the refrigerant pipe exchanges heat with the refrigerant flowing in the refrigerant pipe flowing out of the evaporator. Here, the drain pan heating means is a refrigerant pipe that heats the drain pan in contact with the drain pan .

  When the heat pump is activated, the refrigerant absorbs heat in the air and evaporates in the evaporator. And the gaseous-phase refrigerant | coolant discharged from the evaporator is compressed with a compressor, and becomes high pressure high temperature. The high-temperature and high-pressure refrigerant discharged from the compressor performs heat exchange with, for example, water supplied from the outside in the radiator. The refrigerant discharged from the radiator is expanded in the decompression mechanism and becomes a low-temperature and low-pressure gas-liquid two-phase (or liquid phase).

Here, the drain pan heating means includes a refrigerant pipe included in the heat exchanger and brought into contact with the drain pan, and at least a part of the refrigerant in the refrigerant pipe flowing between the radiator and the pressure reducing mechanism. The drain pan is heated using heat. Therefore, it is possible to prevent the drain pan and the drain outlet provided in the lower part of the evaporator from freezing. Moreover, since the remaining heat after radiating with the radiator is used, the heat efficiency of the heat pump unit does not decrease or does not decrease much. Furthermore, the refrigerant discharged from the radiator and flowing in the refrigerant pipe exchanges heat with the drain pan provided at the lower part of the evaporator, and is further cooled, thereby providing supercooling to the refrigerant flowing out of the radiator. In addition, the refrigerant flowing into the compressor can be heated and brought close to an overheated state.

  The heat pump unit according to the second invention is the heat pump unit according to the first invention, and in the radiator, the refrigerant releases heat to the hot water.

  For example, the temperature of the hot water inlet that performs heat exchange with the refrigerant in the radiator is 20 ° C. or higher. In cold regions such as Europe, it is necessary to perform heating so as to maintain the indoor temperature in winter at 20 ° C. or higher, so the temperature of hot water supplied from the indoor radiator becomes 20 ° C. or higher. Therefore, the temperature of the refrigerant after the heat is released to the hot water by the radiator becomes 20 ° C. or more, and it is sufficiently possible to utilize this remaining heat.

  A heat pump unit according to a third invention is the heat pump unit of the first or second invention, and the heat pump uses carbon dioxide as a refrigerant.

  Until now, fluorocarbons have been widely used as a medium (refrigerant) for transporting heat energy in the refrigeration cycle in the heat pump, but as a countermeasure against global warming, carbon dioxide is being used as a refrigerant.

  A heat pump unit according to a fourth aspect is the heat pump unit according to any one of the first to third aspects, wherein the drain pan heating means is a refrigerant provided between the radiator and the pressure reducing mechanism and in contact with the drain pan. It is piping.

  Here, the refrigerant pipe provided between the radiator and the decompression mechanism is brought into contact with the drain pan, so that at least a part of the heat of the refrigerant flowing between the radiator and the decompression mechanism is used with a simple structure. Thus, the drain pan can be heated.

  A heat pump unit according to a fifth aspect is the heat pump unit according to the fourth aspect, wherein the drain pan heating means further includes a heat transfer member provided at a contact portion between the refrigerant pipe and the drain pan.

  Here, the heat transfer effect between the refrigerant pipe and the drain pan can be increased by providing the heat transfer member at the contact portion between the refrigerant pipe and the drain pan.

  A heat pump unit according to a sixth aspect of the present invention is the heat pump unit according to any one of the first to fifth aspects, wherein the drain pan is provided with a drain port, and the contact portion between the refrigerant pipe and the drain pan is a drain port. Is located near.

  Here, by disposing the contact portion between the refrigerant pipe and the drain pan near the drain port, the drain port can be prevented from freezing.

  A heat pump unit according to a seventh aspect of the present invention is the heat pump unit of the sixth aspect, wherein the outer periphery of the refrigerant pipe is wrapped in a heat insulating material, and a notch is formed in the heat insulating material of the refrigerant pipe located around the drain outlet. ing.

  Here, the outer periphery of the refrigerant pipe is wrapped with a heat insulating material to block heat exchange between the refrigerant pipe and the outside air. Further, the heat insulating material is cut out in the vicinity of the drain port, and the vicinity of the drain port is heated by the residual heat of the refrigerant flowing in the refrigerant pipe. In this way, by heating only the drain pan drain port that is worried about freezing and that requires heating, unnecessary heat loss can be reduced, and the overall heat efficiency of the heat pump unit can be increased.

  A heat pump hot water supply apparatus according to an eighth aspect of the present invention includes the heat pump unit according to any one of the first to seventh aspects, and a hot water storage tank that stores hot water heated by the heat pump unit.

  Here, the hot water heated by the heat pump unit can be stored in a hot water storage tank and used as a hot water circulation heating system or a hot water supply system.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the drain pan and drain outlet provided in the lower part of the evaporator freeze using the residual heat after radiating with a radiator.

<Main configuration of hot water circulation heating system>
The configuration of a hot water circulation heating system including a heat pump unit according to an embodiment of the present invention is shown in FIG. The hot water circulation heating system is a system that circulates hot water in a building to perform heating and has a hot water supply function, and includes a heat pump unit 1, a hot water storage tank 2, a hot water supply heat exchanger 3, a heating circulation circuit 4, and a heating system. A circulation circuit 5, a control unit 7, and indoor radiators 8 and 8 are provided.

  The heat pump unit 1 takes in heat from the outside air by the evaporator 11. Further, the hot water flowing from the hot water storage tank 2 through the hot water circulation circuit 5 is heated by the heat released from the radiator 13.

  The hot water storage tank 2 stores hot water heated by the heat pump unit 1. In addition, a heater 6 is disposed at a substantially central portion in the vertical direction in the hot water storage tank 2, and the heater 6 directly heats the hot water in the hot water storage tank 2.

  The heating circulation circuit 4 is for circulating the hot water stored in the hot water storage tank 2 again through the plurality of radiators 8 outside the hot water storage tank 2 and then returning it to the hot water storage tank 2.

  Each radiator 8 directly takes out the heat of hot water flowing from the hot water storage tank 2 and discharges it into the room. Then, the hot water becomes a low temperature, exits each radiator 8 and flows toward the hot water storage tank 2.

<Configuration of heat pump unit 1>
The heat pump unit 1 shown in FIG. 1 has a refrigerant circuit 16 and boiles water sent from the hot water storage tank 2 to make warm water. The refrigerant circuit 16 is mainly configured by sequentially connecting an evaporator 11, a compressor 12, a radiator 13, and an expansion valve 15 as a pressure reducing mechanism. The refrigerant circuit 16 uses CO2 refrigerant as the refrigerant.

  The evaporator 11 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, exchanges heat with outdoor air, and evaporates the incoming liquid refrigerant. .

  The compressor 12 is a variable capacity compressor capable of varying the operating capacity, and is driven by a motor whose rotational speed is controlled by an inverter in this embodiment.

  The radiator 13 is a heat exchanger that functions as a refrigerant gas cooler. The radiator 13 condenses the high-temperature and high-pressure gas refrigerant compressed in the compressor 12 by exchanging heat with the low-temperature water sent from the circulation pump 51 (dissipating heat to the low-temperature water). The radiator 13 has a gas side connected to the discharge side of the compressor 12 and a liquid side connected to the electric expansion valve 15.

  The electric expansion valve 15 is connected to the liquid side of the evaporator 11 and adjusts the pressure and flow rate of the refrigerant flowing in the evaporator 11.

  Further, the heat pump unit 1 has an outdoor fan 17 as a blower fan for sucking outside air into the unit and exchanging heat with the refrigerant in the evaporator 11 and then discharging the air after heat exchange to the outside. ing. The outdoor fan 17 is a fan that can vary the air volume of air supplied to the evaporator 11.

  Further, a drain pan 19 is provided at the lower portion of the evaporator 11 as a tray for discharging condensed water. As shown in FIG. 2, the shape of the OLE_LINK1 drain pan 19 is a dish shape with a bottom surface of OLE_LINK1 rectangle, and two drain ports 23 are provided. The refrigerant pipe 21 from the radiator 13 is disposed along the bottom surface of the drain pan 19, and is particularly in contact with the vicinity of the drain port 23.

<Configuration of hot water storage tank 2>
The hot water storage tank 2 stores hot water heated by the heat pump unit 1. In addition, a heater 6 is disposed in a substantially central portion of the hot water storage tank 2 in the vertical direction. The heater 6 can directly heat the hot water in the hot water storage tank 2. The heater 6 can store hot hot water in the upper part of the hot water storage tank 2. Although not shown, a plurality of temperature sensors are provided in the hot water storage tank 2 in order to detect the temperature of hot water in each part in the hot water storage tank 2. The plurality of temperature sensors detect the temperature of hot water in each part in the hot water storage tank 2 and send a signal indicating the temperature to the control unit 7.

  A signal indicating the temperature of the hot water in the lower region in the hot water storage tank 2 is used for ON / OFF control of the compressor 12 and the boiling circulation pump 51. That is, the control unit 7 performs ON / OFF control of the compressor 12 and the boiling circulation pump 51 based on the temperature of the hot water in the lower region in the hot water storage tank 2.

<Configuration of circulating circuit 5 for boiling>
The heat pump unit 1 is connected to a hot water storage tank 2 via a boiling circulation circuit 5. The boiling circulation circuit 5 is provided with a boiling circulation pump 51 and a boiling three-way valve 52. The boiling circulation circuit 5 is connected to the second heating forward connection port 42, the heating supply port 53, and the antifreezing water return connection port 54. In addition, the 2nd heating outgoing connection port 42 is an example of a 1st water intake port. The supply port 53 is provided in the lower part of the hot water storage tank 2, and the relatively low temperature hot water in the lower region in the hot water storage tank 2 can be supplied to the boiling circulation pump 51 through the supply port 53. In addition, let the area | region occupied in the hot water storage tank 2 by the comparatively low temperature warm water be the low temperature water area | region Zl as a 2nd area | region.

  The boiling circulation pump 51 sucks hot water in the low-temperature water region Zl in the hot water storage tank 2 and discharges the sucked relatively low-temperature hot water toward the condenser 13. In the radiator 13, the relatively low-temperature hot water is heated by exchanging heat with the CO 2 refrigerant, and becomes high-temperature hot water. The hot hot water that exits the radiator 13 goes to the boiling three-way valve 52. The boiling three-way valve 52 is configured to supply high-temperature hot water heated by the water heat exchanger 13 during the hot water supply operation and the heating operation to the upper region in the hot water storage tank 2 via the second heating forward connection port 42. Shed. Therefore, the second heating / outgoing connection port 42 is a return connection port from which hot hot water flowing out from the supply port 53 of the hot water storage tank 2 and heated by the hydrothermal exchanger 13 of the heat pump unit 1 returns. For this reason, the hot water in the hot water storage tank 2 has a high temperature water area Zh as a first area occupied by hot water at the upper side and a low temperature water area Zl as a second area occupied by relatively low temperature hot water at the lower side. A hot water layer (temperature distribution) is formed.

<Hot water supply piping>
The hot water supply pipe is branched from the water supply pipe to which water is supplied, and is drawn into a hot water supply heat exchanger 3 provided in the hot water storage tank 2, and tap water supplied from the water supply pipe is converted into the hot water supply heat exchanger 3. This is a pipe that exchanges heat with the hot water in the hot water storage tank 2 to supply hot water to the kitchen, bathtub, shower, etc. of the home.

  The hot water supply heat exchanger 3 is formed of a coiled pipe, and is arranged from the low temperature water region Zl to the high temperature water region Zh in the hot water storage tank 2. The tap water supplied to the hot water supply pipe (hereinafter, the tap water flowing through the hot water supply pipe is referred to as hot water supply water) is heated by flowing through the heat exchanger 3 for hot water supply. Specifically, hot water first enters the hot water storage tank 2 from the lower part of the hot water storage tank 2 and flows upward through the hot water supply heat exchanger 3 arranged in the low temperature water region Zl in the hot water storage tank 2. . The hot water flows through the hot water heat exchanger 3 disposed in the high-temperature water region Zh in the hot water tank 2 and then flows out of the hot water tank 2 from the upper part of the hot water tank 2. In addition, the heat exchanger 3 for hot water supply is arrange | positioned so that the heater 6 arrange | positioned in the center part of the up-down direction in the hot water storage tank 2 may be straddled. Here, the hot water supply heat exchanger 3 disposed above the heater 6 is referred to as an upper coil portion 3a, and the hot water supply heat exchanger 3 disposed below the heater 6 is referred to as a lower coil portion 3b.

  In the hot water supply pipe, a hot water supply mixing valve 31 for adjusting the hot water supply temperature to a temperature set by the user with a remote controller or the like is branched from the water supply pipe to the hot water storage tank 2 and for hot water supply. It is provided between piping from the heat exchanger 3 to the home kitchen, bathtub, shower and the like. That is, the hot water mixed by the hot water supply valve 31 is mixed with the tap water supplied from the water supply pipe and the hot water heated by the heat exchanger 3 for hot water supply so that the mixed hot water becomes the set temperature. It is adjusted to.

<Heating circuit 4>
The heating circulation circuit 4 is for circulating the hot water stored in the hot water storage tank 2 again through the plurality of radiators 8 outside the hot water storage tank 2 and then returning it to the hot water storage tank 2. The heating circulation circuit 4 is connected to the first and second heating forward connection ports 41 and 42 and the heating return connection port 43. In addition, the 1st heating outgoing connection port 41 is an example of a 2nd water intake, and the heating return connection port 43 is an example of a return port.

  The first heating / outgoing connection port 41 is for taking out hot water in the hot water storage tank 2. The first heating / outgoing connection port 41 is provided at a substantially central portion in the vertical direction of the hot water storage tank 2, and is positioned near and above the heater 6. Thereby, the hot water immediately after being heated by the heater 6 can be taken out from the first heating forward connection port 41 and sent to the plurality of radiators 8.

  Similarly to the first heating forward connection port 41, the second heating forward connection port 42 is also for taking out hot water in the hot water storage tank 2. The second heating / outgoing connection port 42 is provided in the upper part of the hot water storage tank 2. Thereby, the hot water in the upper region in the hot water storage tank 2 can be taken out from the second heating forward connection port 42 and sent to the plurality of radiators 8. Moreover, the 2nd heating outgoing connection port 42 serves as a heating return connection port.

  Each radiator 8 directly takes out the heat of hot water flowing from the hot water storage tank 2 and discharges it into the room. Then, the hot water becomes a low temperature, flows out of each radiator 8, and flows toward the heating return connection port 43.

  The heating return connection port 43 is provided in the lower part of the hot water storage tank 2. As a result, the hot water discharged from the heating return connection port 43 can be mixed with the hot water in the lower region in the hot water storage tank 2.

  The heating circulation circuit 4 is provided with a bypass pipe 44, a heating mixing valve 45, first and second temperature sensors 46 and 47, a heating circulation pump 48, and a heating three-way valve 49.

  The bypass pipe 44 guides a part of the hot water flowing from the radiator 8 to the heating return connection port 43 to the heating mixing valve 45.

  The heating mixing valve 45 has an inlet through which hot water from the hot water storage tank 2 flows and an inlet through which hot water from the bypass pipe 44 flows. Although described in detail later, the opening degree of each inlet of the heating mixing valve 45 is adjusted by the control unit 7.

  The first temperature sensor 46 detects the temperature of the hot water from the hot water storage tank 2 toward the radiator 8 and sends a signal indicating this temperature to the control unit 7.

  The second temperature sensor 47 detects the temperature of the hot water from the radiator 8 toward the hot water storage tank 2 and sends a signal indicating this temperature to the control unit 7.

<Control unit 7>
The control unit 7 receives a signal indicating the outside air temperature from the outside temperature sensor 18 and also receives a signal indicating the room temperature from an indoor temperature sensor (not shown). The control unit 7 adjusts the opening degree of each of the two inlets of the heating mixing valve 45 based on the signals from the outside air temperature sensor 18 and the first and second temperature sensors 46 and 47, and the heating circulation. The rotational speed of the pump 48 is adjusted. For example, when the outside air temperature is high, the heating mixing valve 45 is adjusted to increase the amount of warm water flowing in from the bypass pipe 44 to lower the going temperature, or the heating circulation pump 48 is rotated at a lower speed to circulate. Lower the return temperature by lowering the flow rate of warm water. On the other hand, when the outside air temperature is low, the heating mixing valve 45 is adjusted to decrease the amount of warm water flowing from the bypass pipe 44 to increase the going temperature, or the heating circulation pump 48 is increased in the number of rotations to circulate. Increase the return temperature by increasing the flow rate of hot water.

<About operation of heat pump unit 1>
When the heat pump unit 1 operates, the CO 2 refrigerant evaporates by absorbing heat in the air sent from the outdoor fan 17 in the evaporator 11. And the gaseous-phase refrigerant | coolant discharged from the evaporator 11 is compressed with the compressor 12, and becomes a high voltage | pressure high temperature refrigerant | coolant. The high-temperature and high-pressure refrigerant discharged from the compressor 12 exchanges heat with the hot water from the hot water storage tank 2 through the hot water circulation circuit 5 in the radiator 13. The refrigerant radiated by heat exchange becomes lower in temperature than before entering the condenser 13 and flows toward the expansion valve 15. Here, the refrigerant piping 21 between the radiator 13 and the expansion valve 15 is in contact with the drain pan 19, and the heat of the refrigerant flowing between the radiator 13 and the expansion valve 15 is used to drain the drain pan 19. 19 and the drain 23 provided in the drain pan 19 are heated. Thereafter, the refrigerant is expanded in the expansion valve 15 to become a low-temperature low-pressure gas-liquid two-phase (or liquid phase).

  OLE_LINK2 FIG. 3 is a ph diagram of the refrigeration cycle of the heat pump unit 1. In the compressor 12, the CO2 refrigerant is compressed to a pressure exceeding the critical pressure, and enters a high temperature and high pressure super maritime state. Transition from point A to point B shown in FIG. At point B, the temperature of the CO2 refrigerant is about 120 ° C.

  In the radiator 13, the CO 2 refrigerant is cooled by exchanging heat with the hot water sent from the hot water storage tank 2, and gradually falls in temperature to shift from the supercritical state to the liquid state. Transition from point B to point C shown in FIG. At point C, the temperature of the CO2 refrigerant is about 32 ° C.

  The CO 2 refrigerant flowing through the refrigerant pipe 21 discharged from the radiator 13 exchanges heat with the drain pan 19 provided at the lower part of the evaporator 11, and is further cooled to move from the C point to the C ′ point in FIG. To do. At the C ′ point, the temperature of the CO 2 refrigerant is about 22 ° C.

  Thereafter, in the expansion valve 15, the CO2 refrigerant is depressurized and enters a low-temperature and low-pressure gas-liquid two-phase (or liquid-phase) state. Transition from the point C 'shown in FIG. At the point D after decompression, the temperature of the CO2 refrigerant is about -10 ° C.

In the evaporator 11, the CO 2 refrigerant takes in heat from the outside air and evaporates to become a low-temperature and low-pressure gas and is sucked into the compressor 12 again. Transition from point D to point A shown in FIG. In the evaporator 11, the CO2 refrigerant is only changed from gas-liquid two-phase (or liquid-phase) to gas, and the temperature remains at about -10 ° C.
OLE_LINK2 <Characteristics of heat pump unit>
(1)
In this heat pump unit 1, the refrigerant pipe 21 between the radiator 13 and the expansion valve 15 is brought into contact with the vicinity of the drain port 20 of the drain pan 19 provided at the lower part of the evaporator 11, and the heat of the refrigerant flowing through the refrigerant pipe 21. The drain pan 19 and the drain port 20 are heated using Therefore, in the hot water circulation heating system used in a cold district, it is possible to prevent the drain pan 19 and the drain outlet 20 from freezing.

(2)
In cold regions such as Europe, it is necessary to perform heating so that the indoor temperature in winter is maintained at 20 ° C or higher. Therefore, the temperature of the hot water returned to the hot water tank after the heat exchange with the indoor radiator 8 is 20 ° C or higher. It is. Therefore, the temperature of the refrigerant after releasing heat to the hot water by the radiator 13 becomes 20 ° C. or higher, and this residual heat can be used.

(3)
Moreover, since the residual heat after radiating with the radiator 13 is used, the heat exchange efficiency in the radiator 13 is not lowered, and thus the thermal efficiency of the entire heat pump unit 1 is not lowered. In addition, since the drain pan 19 and the drain outlet 20 are heated by the refrigerant after heat dissipation, the drain pan 19 and the drain outlet 20 can be prevented from freezing, and normal operation can be continued even in cold regions. It is also possible to improve.

(4)
In the heat pump unit 1, the refrigerant pipe 21 provided between the radiator 13 and the expansion valve 15 is brought into contact with the drain pan 19, so that the structure between the radiator 13 and the expansion valve 15 is simplified. The drain pan can be heated using the heat of the refrigerant flowing through the.

(5)
In addition, heat is required for the drain pan to dissipate heat, but by dissipating heat to the drain pan, the refrigerant density before the expansion valve can be increased and the refrigerant in the evaporator can be moistened. Even with the same evaporation capability, it is possible to use latent heat, and the evaporation temperature becomes slightly higher, and the efficiency is improved. This is particularly significant when the return temperature from the radiator is high and improves efficiency.

<Other examples>
The configuration of the heat pump unit 100 according to another embodiment is shown in FIG. About the same structure as the heat pump unit of FIG. 1, the same drawing code | symbol is used and description about a specific structure is abbreviate | omitted.

  The heat pump unit 100 in FIG. 4 further includes a heat exchanger 14. In the heat exchanger 14, heat exchange is performed between the low-pressure low-temperature refrigerant that flows out of the evaporator 11 and flows into the compressor 12, and the high-pressure refrigerant that flows out of the radiator 13 and flows into the expansion valve 15.

  As shown in FIGS. 4 and 5, the heat exchanger 14 is disposed on the drain pan 19, and includes a refrigerant pipe 211 that connects the radiator 13 and the expansion valve 15, the evaporator 11, and the compressor 12. And a refrigerant pipe 212 connecting the two. As shown in FIG. 5, the refrigerant pipes 211 and 212 included in the heat exchanger 14 are in contact with the drain pan 19 in a state where they overlap each other, thereby constituting the drain pan heating means 201. The drain pan 19 has a drain port 23, and a part of the drain pan heating means 201 including the refrigerant pipes 211 and 212 is disposed in the vicinity of the drain port 23.

  FIG. 6 is a ph diagram of the refrigeration cycle of the heat pump unit 100. In the compressor 12, the CO2 refrigerant is compressed to a pressure exceeding the critical pressure, and enters a high temperature and high pressure super maritime state. Transition from point A to point B shown in FIG. At point B, the temperature of the CO2 refrigerant is about 120 ° C.

  In the radiator 13, the CO 2 refrigerant is cooled by exchanging heat with the hot water sent from the hot water storage tank 2, and gradually falls in temperature to shift from the supercritical state to the liquid state. Transition from point B to point C shown in FIG. At point C, the temperature of the CO2 refrigerant is about 32 ° C.

  Here, since the heat exchanger 14 is provided, the liquid CO 2 refrigerant at about 32 ° C. discharged from the radiator 13 and flowing in the refrigerant pipe 211 is about −10 flowing in the refrigerant pipe 212 flowing out of the evaporator 11. Heat exchange is performed with a gaseous CO 2 refrigerant at 0 ° C., and heat exchange is performed with the drain pan 19 provided at the lower portion of the evaporator 11, thereby further cooling. When the heat exchanger 14 shown in FIG. 3 is not provided, it is further cooled beyond the C ′ point (about 22 ° C.) and moved to the C ″ point. At the C ″ point, the temperature of the CO 2 refrigerant is about 12 ° C. Thereby, supercooling can be imparted to the refrigerant that has flowed out of the radiator 13, and the refrigerant that flows into the compressor 12 can be heated to approach the overheated state.

  Thereafter, in the expansion valve 15, the CO2 refrigerant is depressurized and enters a low-temperature and low-pressure gas-liquid two-phase (or liquid-phase) state. Transition from the point C ″ shown in FIG. 6 to the point D is performed. At the point D after decompression, the temperature of the CO2 refrigerant is about -10 ° C.

  In the evaporator 11, the CO 2 refrigerant takes in heat from the outside air and evaporates to become a low-temperature and low-pressure gas and is sucked into the compressor 12 again. Transition from the point D shown in FIG.

  Here, since the heat exchanger 14 is provided, about −10 ° C. gaseous CO 2 refrigerant flowing in the refrigerant pipe 212 flowing out of the evaporator 11 is discharged from the radiator 13 and about 32 flowing in the refrigerant pipe 211. Heat exchange is performed with the liquid CO 2 refrigerant at 0 ° C., and the point A ′ is shifted to the point A. In this process, the temperature of the CO 2 refrigerant remains at about −10 ° C., and the dryness of the gas increases. For this reason, it is possible to prevent wet compression from occurring in the compressor 12 and to enable stable operation.

<Modification>
(A)
The drain pan heating means 201 shown in FIG. 5 is in direct contact with the drain pan 19 with the refrigerant pipes 211 and 212 included in the heat exchanger 14 being overlapped, and heats the entire drain pan 19 including the drain port 23. It has a structure. However, only the drain outlet 23 of the drain pan 19 can be heated. For example, as shown in FIG. 7, the outer periphery of the heat exchanger 14 in which the refrigerant pipes 211 and 212 are stacked is wrapped with a heat insulating material 25 to block heat exchange between the refrigerant pipes 211 and 212 and the outside air. Further, the heat insulating material 25 is cut out in the vicinity of the drain port 23, and the vicinity of the drain port 23 is heated by the residual heat of the liquid CO 2 refrigerant flowing in the refrigerant pipe 211.

  In this way, unnecessary heat loss can be reduced by heating only the drain port 23 of the drain pan 19 that is worried about freezing and that requires heating.

(B)
As shown in FIG. 8, a heat transfer member 24 may be provided at the contact portion between the refrigerant pipe 211 and the drain pan 19 in the vicinity of the drain port 23 to enhance heat transfer at the contact portion between the refrigerant pipe 211 and the drain pan 19. Is possible.

(C)
In the drain pan heating means shown in FIG. 3, the refrigerant pipe 21 from the radiator 13 is in direct contact with the drain pan 19 as it is, and the entire drain pan 19 including the drain port 23 is heated. However, only the drain outlet 23 of the drain pan 19 can be heated. As in (A) above, the outer periphery of the refrigerant pipe 21 is wrapped with a heat insulating material 25, and the heat insulating material 25 is cut out in the vicinity of the drain port 23, and the vicinity of the drain port 23 is heated by the residual heat of the liquid CO 2 refrigerant flowing in the refrigerant pipe 21. To do.

  Further, similarly to the above (B), the heat transfer member 23 is provided at the contact portion between the refrigerant pipe 21 and the drain pan 19 in the vicinity of the drain port 23 to enhance heat transfer at the contact portion between the refrigerant pipe 21 and the drain pan 19. Is also possible.

(D)
In the heat pump unit 1 described above, all the refrigerant discharged from the radiator 13 and supplied to the expansion valve 15 heats the drain port 23 of the drain pan 19 via the refrigerant pipe 21. However, at least two piping paths are provided between the radiator 13 and the expansion valve 15, a switching valve is provided between them, and only a part of the CO 2 refrigerant discharged from the radiator 13 is used for heating the drain pan 19. However, other portions may be directly supplied to the expansion valve 15.

  The heat pump unit 100 may adopt the same structure, and only a part of the CO 2 refrigerant discharged from the radiator 13 may be supplied to the heat exchanger 14 and the other part may be directly supplied to the expansion valve 15.

The figure which shows the structure of the hot water circulation heating system which concerns on one Embodiment of this invention. The figure which shows the cycle of a heat pump unit (Ph diagram). The figure which shows a part of heating means of a drain pan. The figure which shows a part of structure of the warm water circulation heating system of another Example. The figure which shows a part of structure of the heating means of the drain pan of another Example. The figure (Ph diagram) which shows the cycle of the heat pump unit of another Example. The figure which shows a part of heating means of the drain pan of a modification. The partial enlarged view of a heating means.

DESCRIPTION OF SYMBOLS 1,100 Heat pump unit 2 Hot water storage tank 11 Evaporator 12 Compressor 13 Radiator 14 Heat exchanger 15 Expansion valve 19 Drain pan 20, 201 Drain pan heating means 21, 211 Refrigerant piping from radiator 23 Drain outlet 24 Heat transfer member 25 Insulation member

Claims (5)

An evaporator (11) for absorbing heat in the air and evaporating the refrigerant;
A compressor (12) for compressing the gas-phase refrigerant from the evaporator and discharging it as a high-pressure refrigerant;
A radiator (13) for releasing the heat of the high-temperature refrigerant supplied from the compressor;
A decompression mechanism (15) for expanding the refrigerant from the radiator;
A drain pan (19) provided at the bottom of the evaporator;
A heat exchanger (14) for causing heat exchange between the refrigerant from the evaporator toward the compressor and the refrigerant from the radiator toward the decompression mechanism, and for providing supercooling to the refrigerant flowing out of the radiator;
In a heat pump unit comprising drain pan heating means (20) for heating the drain pan using heat of at least a part of the refrigerant flowing between the radiator and the decompression mechanism,
The drain pan heating means includes
Refrigerant pipes (211 and 212) that are included in the heat exchanger and that heat the drain pan in contact with the drain pan;
The refrigerant flowing in the refrigerant pipe exchanges heat with a drain pan provided in the lower part of the evaporator and is further cooled, thereby providing supercooling to the refrigerant flowing out of the radiator and a compressor. heating the refrigerant flowing Ki out to approach the overtemperature condition,
The drain pan is provided with a drain (23),
The refrigerant pipe is disposed near the drain port,
The outer periphery of the refrigerant pipe is wrapped in a heat insulating material (25),
A notch is formed in the heat insulating material of the refrigerant pipe located around the drain outlet,
Heat pump unit. In the radiator, the refrigerant releases heat to the hot water.
The heat pump unit according to claim 1. The refrigerant is carbon dioxide;
The heat pump unit according to claim 1 or 2. The drain pan heating means includes
A heat transfer member (24) provided at a contact portion between the refrigerant pipe and the drain pan;
The heat pump unit according to claim 1 . The heat pump unit (1) according to any one of claims 1 to 4 ,
A hot water storage tank (2) for storing hot water heated by the heat pump unit (1);
Heat pump water heater with

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